Python:创建异常日志装饰器

Python: How to Create an Exception Logging Decorator

exception_decor.py

import functools
import logging
 
def create_logger():
 """
 Creates a logging object and returns it
 """
 logger = logging.getLogger("example_logger")
 logger.setLevel(logging.INFO)
 
 # create the logging file handler
 fh = logging.FileHandler("/path/to/test.log")
 
 fmt = '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
 formatter = logging.Formatter(fmt)
 fh.setFormatter(formatter)
 
 # add handler to logger object
 logger.addHandler(fh)
 return logger
 
 
def exception(function):
 """
 A decorator that wraps the passed in function and logs 
 exceptions should one occur
 """
 @functools.wraps(function)
 def wrapper(*args, **kwargs):
 logger = create_logger()
 try:
 return function(*args, **kwargs)
 except:
 # log the exception
 err = "There was an exception in "
 err += function.__name__
 logger.exception(err)
 
 # re-raise the exception
 raise
 return wrapper

在该代码中,有两个函数。第一个函数创建了日志对象并返回该日志对象。第二个函数是我们的装饰器函数。我们在一个try/except中封装传递的函数,当logger中发生任何异常的时候,进行日志记录。并且我还记录了当异常发生时的函数名称。

现在让我们测试下该装饰器。

 from exception_decor import exception
 
 @exception
 def zero_divide():
 1 / 0
 
 if __name__ == '__main__':
 zero_divide()

运行以上测试代码后,会出现以下错误日志:

2016年06月09日 08:26:50,874 - example_logger - ERROR - There was an exception in zero_divide
Traceback (most recent call last):
 File "/home/mike/exception_decor.py", line 29, in wrapper
 return function(*args, **kwargs)
 File "/home/mike/test_exceptions.py", line 5, in zero_divide
 1 / 0
ZeroDivisionError: integer division or modulo by zero

传递一个 logger 到装饰器

# exception_logger.py
 
import logging
 
def create_logger():
 """
 Creates a logging object and returns it
 """
 logger = logging.getLogger("example_logger")
 logger.setLevel(logging.INFO)
 
 # create the logging file handler
 fh = logging.FileHandler(r"/path/to/test.log")
 
 fmt = '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
 formatter = logging.Formatter(fmt)
 fh.setFormatter(formatter)
 
 # add handler to logger object
 logger.addHandler(fh)
 return logger
 
logger = create_logger()

现在修改前面出现的装饰器,以便可以接受 logger 作为参数。

# exception_decor.py
 
import functools
 
 
def exception(logger):
 """
 A decorator that wraps the passed in function and logs 
 exceptions should one occur
 
 @param logger: The logging object
 """
 
 def decorator(func):
 
 def wrapper(*args, **kwargs):
 try:
 return func(*args, **kwargs)
 except:
 # log the exception
 err = "There was an exception in "
 err += func.__name__
 logger.exception(err)
 
 # re-raise the exception
 raise
 return wrapper
 return decorator

最后修改测试脚本:

from exception_decor import exception
from exception_logger import logger
 
@exception(logger)
def zero_divide():
 1 / 0
 
if __name__ == '__main__':
 zero_divide()